Coextruded Foil Composite Material and Its Use in Card Bodies

ABSTRACT

A composite film material usable in a data carrier card body includes a first outer plastic layer, an inner plastic layer and a second outer plastic layer, all the layers together forming a coextruded composite. The plastic material of the first outer layer is a polyethylene terephthalate glycol copolymer (PETG) or contains a PETG, the plastic material of the inner layer is a thermoplastic elastomer (TPC) or contains a TPC, and the plastic material of the second outer layer is a PETG or contains a PETG.

BACKGROUND OF THE INVENTION

A. Field of the Invention

This invention relates to a foil composite material, to a method formanufacturing the foil composite material, as well as to a card body, inparticular a card body for a portable data carrier, which contains thefoil composite material, and to a method for manufacturing the cardbody.

B. Related Art

In the production of card bodies, in particular for portable datacarriers, such as e.g. chip cards, several plastic foils lying one overthe other are laminated to each other. As plastic foils there areusually employed thermoplastic foils because of their goodlaminatability, e.g. foils made of polyvinyl chloride, polycarbonate,polypropylene, polyethylene terephthalate or thermoplasticpolyurethanes. A disadvantage of card bodies made of such thermoplasticfoils is their deficient mechanical properties with regard to bendingstress and the action of impact force. There result stresses in the cardbody, and finally cracks. The installation of electronic modules alsousually leads to stresses, a weakening of the card body, and ultimatelyto an elevated susceptibility to cracks and breaks.

To improve the mechanical properties of such card bodies it isadvantageous to employ foils made of thermoplastic elastomer, forexample based on urethane, within the framework of the laminatingprocess. These foils are exceptionally elastic and can considerablyimprove the bending strength and breaking strength of the cardconstruction. In the print EP 0 430 282 A2 there is described a cardbody in the form of a multilayer identification card wherein a layer ofthermoplastic elastomer is respectively provided between the card coreand corresponding cover foils.

However, it is very difficult to process foils made of thermoplasticelastomer, so-called TPE foils, within the framework of a laminatingprocess upon the manufacture of a card body. On account of their highelasticity the foils are very “limp”. The lack of stiffness leads toproblems upon processing in the production machines, and the lowdimensional stability can also cause register problems upon printing ofthe foils. In addition, the material tends to flow out upon laminating.Further, such foils possess a low glass transition range, which liesunder 0° C., whereby it remains flexible and does not become brittle inthis temperature range. Furthermore, the foils tend to block uponstacking, so that the foils in a stack are hard to single and transport.To obtain a sufficient connection stiffness upon lamination of suchfoils to other materials, it is moreover necessary to reach the glasspoint of the respective other material. Because this glass pointregularly lies far above the glass transition range of thermoplasticelastomers, this frequently leads to the thermoplastic elastomerfloating off, in connection with the dependence on the strength of theviscosity drop in the corresponding temperature range. This has theconsequence that the employed laminating machines must often be cleaned.In some cases the foils adjacent to the thermoplastic elastomer can evenlikewise start to flow, and deform a printed image located thereon.Although it is possible to laminate at lower temperatures to therebyprevent the foils from floating off, an insufficiently good laminatebond is normally obtained upon laminating at low temperatures.

Hence, it is desirable to combine the positive properties ofthermoplastic foils and of foils made of thermoplastic elastomer in asingle foil material. A solution approach in this direction is disclosedin the document EP 0 384 252 B 1. The therein described foil compositematerial has a multiplicity of layers, whereby a middle layer is made ofthermoplastic elastomer. This layer is adjoined by layers made ofthermoplastic plastics. Upon the manufacture of the composite materialthere are applied to a foil forming the middle layer the further layers.One application method is simultaneous extrusion, whereby the layers aremerged after leaving the extruder.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a foil material that issuitable for use as a layer in a card body. In particular, the foilmaterial should be readily processable within the framework of producinga card body, and guarantee good mechanical properties of the card body.Desired properties of such a foil material are

-   -   high flexibility in order to guarantee the desired bending        strength, in particular dynamic bending strength, of the card;    -   the capability to avoid stresses, cracks and breaks in the card,        in particular also upon installation of electronic modules into        the card;    -   good laminatability to common card materials, in particular        thermoplastic foils, preferably without auxiliary layers;    -   good printability, preferably without pretreatment for printing;    -   good dimensional stability upon manufacture and processing;    -   simple, and preferably inexpensive, manufacturability;    -   good handling upon further processing, in particular avoidance        of blocking, as well as    -   higher chemical resistance to standard materials.

Another object of the present invention is to provide a card body, inparticular a card body for a portable data carrier, that avoids thedisadvantages of the prior art. In particular, the card body shouldreadily tolerate the installation of electronic modules and have goodresistance to stress cracks and breaks, for example upon bending stressand the action of impact force.

According to the invention there is provided a foil composite materialthat has at least three layers, whereby an inner layer made of athermoplastic elastomer is covered on both its surfaces by outer layersmade of thermoplastic polymer. Such a foil composite material combinesthe advantageous elasticity properties of the elastomer with theadvantageous properties of the thermoplastic with regard tolaminatability and handling. The manufacture of such a compositematerial raises technical problems, because the employed materials andprocess parameters must be carefully coordinated with each other toachieve the desired foil properties.

If thermoplastic polymer and elastomer are separately extruded andmerged only immediately after leaving the respective extruder nozzle,the mutual adhesive strength of the partial layers may be deficient, sothat upon stress in some cases there may occur a partial separation ofthe foil composite material into its individual layers. According to theinvention, hence all employed materials still in a molten state aremerged into the foil composite material prior to leaving the extrudernozzle. Only after leaving the extruder nozzle the foil compositematerial cools down and becomes solid, that is, the foil compositematerial as a whole cools down and becomes solid and thus forms aso-called coextrusion foil. This procedure requires that thethermoplastic plastic material and the thermoplastic elastomer must beprocessed at the same temperature or at least within a commontemperature range. Thermoplastics typically have a slightly highermelting or processing temperature than thermoplastic elastomers. Ifthermoplastic elastomers are heated to the typical processingtemperatures of thermoplastics, thermoplastic elastomers tend, more thanthermoplastics, to thermal degradation, which in turn leads todecreasing viscosity and thus to worse foil bond between thermoplasticplastic and thermoplastic elastomer. Furthermore, thermoplastic plasticand thermoplastic elastomer of course must not repel each other, rather,they must be well compatible with each other and bond to each other, sothat they do not delaminate when they are later present in aheavily-used card body. Comparable rheological properties, i.e.comparable melt viscosities, in thermoplastic and thermoplasticelastomer promote a homogeneous melt superimposition and improve themutual adhesive strength of the layers.

Besides the careful coordination of thermoplastic plastic material andthermoplastic elastomer, one must of course also make sure thatextruders are selected whose screw geometries allow the processing ofthe selected material and make possible the respective necessarythroughput for the desired layer thicknesses. In particular, acontinuous flow stream of the thermoplastic elastomer must beguaranteed, so as to avoid the danger of thermal degradation and thusthe deterioration of the rheological properties of the thermoplasticelastomer.

According to the invention it was found that the requirements for a foilto be used as a layer in a card body are fulfilled in the optimal waywhen the inner plasticlayer of the foil composite material ismanufactured of a thermoplastic copolyester elastomer, and the two outerplastic layers are manufactured of a polyethylene terephthalate glycolcopolymer (PETG), the so-called glycol-modified polyethyleneterephthalate. One has to bear in mind here that the thermoplasticcopolyester elastomer as well as the PETG respectively only representthe plastic materials of the inner layer or of the outer layers. Thematerials for the inner layer or the outer layers may also contain,besides the plastic material, usual additives, for example colorpigments, oxidation stabilizers, flame retardants, optical brighteners,fillers, UV stabilizers, release additives and other auxiliary agents.Color pigments can simultaneously act as fillers. The usual extenderscan also be contained, but preferably the layers are free of extenders.In general, the admixture of auxiliary agents is preferably kept low soas to interfere with the coordination of the plastic materials as littleas possible.

The two outer plastic layers can be identical or different. Althoughboth outer plastic layers preferably consist of PETG, they can differwith regard to the PETG type used, with regard to their thickness, orwith regard to their accessory agents. For example, one of the outerplastic layers could contain an antiblocking agent, while the other oneof the outer plastic layers consists of 100% PETG. Preferably, bothouter plastic layers are identical.

The foil composite material according to the invention may also consistof more than three layers. According to an embodiment of the foilcomposite material according to the invention, one or both outer plasticlayers respectively consist of two partial layers, an interior outerlayer which borders on the inner plastic layer, and an exterior outerlayer. Preferably, the layer construction of the foil composite materialis symmetrical with regard to the number of outer layers, i.e. eitherboth outer layers respectively consist of only one layer, or both outerlayers respectively consist of two partial layers. The two partiallayers of an outer layer can also differ with regard to the PETG typeused, with regard to their thickness, and with regard to their accessoryagents. According to a preferred embodiment, the respectively exteriorouter layer contains a small amount of an antiblocking agent, but theinterior outer layer not.

According to a different embodiment, the inner plastic layer consists ofmore than one layer, for example of two or three layers. These layerscan in turn be identical or different, i.e. differ with regard to thethermoplastic copolyester elastomer used, with regard to their thicknessand/or with regard to their accessory agents. Preferably, however, thelayer construction is symmetrical at least with regard to the number ofinner layers. A construction with several partial layers can be veryadvantageous for example when the inner plastic layer is to have a highthickness, but the available extruders do not have the required flowrate. The extrusion process after all must be carried out quickly, sothat at the necessary extrusion temperatures no thermal degradation ofthe thermoplastic copolyester elastomer takes place.

For the inner layer or for the partial layers of the inner layer therecan be used a single thermoplastic copolyester elastomer or a mixture ofthermoplastic copolyester elastomers. The elastomers must, of course, bereadily intermiscible and compatible with each other, i.e. they musthave comparable material properties and processing properties.

Thermoplastic copolyester elastomers are available with Shore D hardnessfrom 25 to 70 and with different elongation at break (150 to over 300%).The processing temperatures lie between 200 and 240° C. The meltingviscosities (MFI), for example at 2.16 kg and 230° C., can also varybetween 3 and 50 cm³/10 min. For the purposes of the present invention,thermoplastic copolyester elastomers (TPC) are preferably used, whoseShore D hardness lies in the range of 33 to 55, whose elongation atbreak is greater than 300%, and whose melt viscosity lies in the rangeof 7 to 11 cm³/10 min. This melt viscosity is comparable to that ofPETG.

Particularly preferred TPC materials are thermoplastic polyesterelastomers of the polyether type. A particularly preferred TPC materialis Arnitel VT 3104 (DSM Engineering Plastics).

The thickness of the foil composite material according to the inventionvaries, depending on the place in the layer sequence of a card bodywhere the foil composite material is to be provided. When the foilmaterial is used as an intermediate layer (inlay), total layerthicknesses in the range of about 50 to 350 μm, for example 240 μm, arepreferred. When the foil composite material according to the inventionis used as a cover layer (overlay foil), total layer thicknesses in therange of about 80 μm to 130 μm, for example 105 μm, are preferred.Referring to the total layer thickness as 100%, about 10 to 30%respectively falls on the first and the second outer plastic layer here,and accordingly about 80 to 40% on the inner plastic layer. It generallyapplies that the higher the proportion of the TPC material in the totallayer thickness, the better the elasticity properties of the foilcomposite material. With given TPC content, the advantageous effects ofthe foil composite material according to the invention in general arethe more pronounced, the further outward the foil composite material islocated in the card body.

It is further pointed out that each of the above-mentioned layers canconsist of a mixture of polymers, for example of a mixture of PETG andTPC, whereby the content of TPC should be the more, the further inwardthe layer is located, and the content of PETG should be the higher, thefurther outward the layer is located. The two outermost layers or thetwo outermost partial layers of the foil composite material shouldcontain exclusively PETG as a plastic material. The particular advantageof the present invention, however, is that no polymer mixtures have tobe manufactured for obtaining gradations in the properties of theindividual layer materials and thus a good mutual connecting strength ofthe layers. Rather, upon using PETG and thermoplastic copolyesterelastomers without compoundings, i.e. each with only TPC and only PETG,good bond values of the foil composite material (adhesion strengthgreater than 30 N/cm) can be achieved. Simultaneously, the elastomerproportion is high and the processing uncomplicated.

The manufacture of the foil composite material according to theinvention is effected by coextrusion. In so doing, the materialsprovided for the individual layers of the foil composite materialaccording to the invention are respectively melted in suitable extrudersand supplied to a wide slot nozzle or a so-called feedblock. In thenozzle or the feedblock they are merged in the provided layer sequenceand jointly extruded through the nozzle. It is of essential significancethat the individual plastic melts are merged prior to their dischargefrom the wide slot nozzle. It is also of significance that the extrusiontemperature and the extrusion speed are coordinated with the materialsused. The temperatures of the extrusion nozzle can typically lie in therange between 210 and 260° C., whereby it must be taken into accountthat at higher temperatures the thermoplastic copolyester elastomermaterial can thermally decompose, so that then a correspondingly highextrusion speed must be ensured. Process data for two exemplaryformulations are stated in connection with the FIGS. 1 and 2. Prior toprocessing all materials must be predried, since they are hygroscopicand through the absorbed moisture in the processing operation they canbe degraded through hydrolytic digestion in the extruder. The moisturecontent should not exceed 0.05%.

The foil composite material according to the invention is in particularsuitable for being used as a layer in the layer construction of a cardbody in order to improve the mechanical properties of the card body.

Card bodies, in particular card bodies for chip cards and other datacarriers, typically consist of a multiplicity of layers which areinterconnected by laminating. The individual layers usually consist ofthermoplastic polymeric materials, such as polyvinyl chloride,polycarbonate or polyethylene terephthalate. Between the layers or inrecesses of the layers there can be located electronic components andimprinted antennas. As at least one of the layers of the card body herethere is used a foil composite material according to the invention. Inparticular, the foil composite material according to the invention isused as one or as both cover layers (overlay foil) of the card body.Alternatively or additionally, the foil composite material according tothe invention can be provided as an intermediate layer within the cardconstruction (inlay foil).

For manufacturing the card body, the plastic foils that are to form thelater card body are laminated to each other. Laminating can be effectedin a single operation, i.e. all foil materials that are to form the cardbody are stacked and laminated in one operation. Alternatively,laminating can be carried out in two or more operations, that is, only aportion of the foils is respectively laminated jointly into a partialstack, and the partial stacks are then stacked and laminated into thecard body in a further operation later. A good laminate bond is obtainedhere by laminating at a suitable pressure and at a temperature between120° C. and 200° C., in particular between 130° C. and 180° C.,preferably between 140° C. and 160° C.

Preferably, laminating is carried out in a heating station and a coolingstation. The laminating time preferably lies respectively between 10minutes and 25 minutes in the heating and/or cooling station.

The card bodies according to the invention typically have totalthicknesses in the range of about 0.5 to 1.0 mm. The total thickness ofthe foil composite material according to the invention normally liesbetween 50 μm and 350 μm, depending on the place in the layeredcomposite of the card body where the foil composite material is to beused. Inlay foils are usually thicker than overlay foils, whereby thetotal thickness for inlay foils typically lies in the range of 200 μm to280 μm, and the total thickness for overlay foils typically lies in therange of 80 gm to 130 μm. The foil composite materials according to theinvention, due to their outer layers made of PETG, fuse very well withneighboring layers of the card-body layer construction, so that a stablecard-body laminate bond is obtained. Laminating adhesives can be used,but they are not necessary. Simultaneously, the PETG outer layersensure, when the foil composite material according to the invention isused as an overlay foil, that the card bodies can be printed and handledwithout any problems, and do not tend to block.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will hereinafter be illustrated further on the basis ofFigures. It is pointed out that the figures are not true to proportionand not true to scale. Moreover, it is pointed out that the Figures areonly intended to explain the invention more closely and are by no meansto be understood as restrictive. The same reference numbers designatethe same elements.

There are shown:

FIG. 1 a section through a foil composite material according to theinvention having an inner plastic layer, two first outer plastic layersand two second outer plastic layers,

FIG. 2 a section through a foil composite material according to theinvention having an inner plastic layer which consists of an interiorinner layer and two exterior inner layers, and having a first outerplastic layer and a second outer plastic layer,

FIG. 3 a section through a foil composite material according to theinvention having an inner plastic layer, a first outer plastic layer anda second outer plastic layer,

FIG. 4 a section through a card body according to the invention havingtwo foil composite materials according to the invention as cover layers,

FIG. 5 a section through a card body according to the invention havingtwo foil composite materials according to the invention as intermediatelayers, and

FIG. 6 a section through a card body according to the invention havingtwo foil composite materials according to the invention as cover layers.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows a first embodiment of a foil composite material 4 accordingto the invention. In the represented embodiment, the foil compositematerial has five layers, an inner plastic layer 3, a first outerplastic layer 1 and a second outer plastic layer 2, whereby the outerplastic layer 1 consists of an interior partial layer 11 and an exteriorpartial layer 12, and the outer plastic layer 2 consists of an interiorpartial layer 21 and an exterior partial layer 22. The inner layer 3consists of 100% thermoplastic copolyester elastomer or a mixture ofthermoplastic copolyester elastomers, and the first outer plastic layer1 and the second outer plastic layer 2 consist of thermoplastic plasticmaterial, whereby the two interior outer layers 11, 21 consist of 100%PETG, while the two exterior outer layers 12, 22, contain, in additionto PETG, an antiblocking agent, for example about 4 wt. % antiblockingagent, with the balance being PETG. The contents are always stated inwt. %.

The manufacture of the foil composite material 4 can be effected forexample by melting granules with three different compositions (granulesA: 96% PETG+4% antiblocking agent; granules B: 100% PETG; granules C:100% TPC) in three extruders A, B, C, and merging the correspondingmolten streams (material A from extruder A, material B from extruder B,material C from extruder C) in a feedblock and jointly extruding themthrough a wide slot nozzle. In the represented embodiment, the foilcomposite material is symmetrical in construction, i.e. the interiorouter layers 11, 21 and the exterior outer layers 12, 22 respectivelyhave the same composition and the same thickness. This is notcompulsory. Rather, the interior outer layers 11, 21 or the exteriorouter layers 12, 22 can respectively differ from each other, for examplecontain different PETG, have a different thickness or have a differentcontent of antiblocking agent. In such a case, correspondingly moreextruders are necessary in a modified feedblock or wide slot nozzlearrangement. Preferably, however, the foil composite materials aresymmetrically constructed, for reasons of an easier manufacturability,on the one hand, and since an unsymmetrical construction usuallyprovides no advantages, on the other hand.

In the represented embodiment, the inner plastic layer 3 is the thickestlayer. This usually will actually be so in practice, since a proportionof TPC material as high as possible is desired, in order to achieve ahigh elasticity of the foil composite material 4. Exemplary layerthicknesses are respectively about 10% of the total thickness for thelayers 12, 22, respectively 20% of the total layer thickness for thelayers 11, 21, and about 40% of the total layer thickness for the layer3.

The following extruder settings achieved good results:

Temperature [° C.] Feed zone [° C.] Extruder A 220-260 40-60 Extruder B225-250 40-60 Extruder C 215-245 40-70 Nozzle 210-260

The respective most favorable extruder settings can vary in dependenceon the extruders employed (throughput, screw geometries or the employedmaterials and their residual moisture content). They provide informationfor orientation, which a person skilled in the art can optionally adaptto the given extruder configurations and given material facts by a fewroutine tests.

FIG. 2 shows a different embodiment of a foil composite material 4according to the invention in cross section. In this embodiment, theinner plastic layer consists of an interior partial layer 31 and twoexterior partial layers 32, 33. Located thereon are a first outerplastic layer 1 and a second outer plastic layer 2. The inner layers 31,32, 33 in turn consist of thermoplastic copolyester elastomer (TPC),whereby all inner layers can consist of the same TPC material or ofdifferent TPC materials. If desired, for one or several of the innerlayers 31, 32, 33 there can also be employed a mixture of TPC materials,or a mixture of one or several TPC materials with a thermoplastic, forexample PETG. In this way gradations can be produced, i.e. a gradualtransition from, for example, a layer 31 made of 100% TPC material overa layer 32 or 33 made of TPC material with PETG admixture to a layer 1or 2 made of 100% PETG. It is preferred, however, to use pure TPCmaterial, in particular the same TPC material, for all inner layers 31,32, 33. The special advantage of the present invention lies in the factthat upon using thermoplastic copolyester elastomers for the innerlayers in combination with PETG for the outer layers, no compoundingsare necessary for producing compatible transitions between the layers.

The manufacture of the foil composite material 4 represented in FIG. 2can be effected analogously to the foil composite material representedin FIG. 1. That is, in an extruder A for example a plastic material madeof 96% PETG with 4% antiblocking agent is melted for the outer layers 1and 2 and fed to a wide slot nozzle, and in two extruders B and C aplastic material made of 100% TPC is respectively melted and fed to thewide slot nozzle, whereby the feeding is effected such that the layerconstruction represented in FIG. 2 is produced. Extruder C, whichextrudes the material for the thickest inner layer 31, must have thegreatest flow rate. However, it is also possible that the extruder Cdoes not have the greatest flow rate. The flow rate of the individualextruders can be generally adapted to the production conditions and tothe specific requirements of the plastic material respectively used andthe layer to be manufactured therewith.

In the following there are stated exemplary extruder settings formanufacturing the foil composite material 4, which optionally are to beadapted to the extruder configurations and material moistures present inthe respective individual case.

Temperature [° C.] Feed zone [° C.] Extruder A 220-250 40-60 Extruder B215-240 40-60 Extruder C 215-240 40-60 Nozzle 210-250

For all embodiments and layer sequences of the foil composite materialaccording to the invention it has proven to be particularly useful touse the following materials:

Arnitel VT 3104 as a thermoplastic copolyester elastomer,Eastman PETG 6763 as a thermoplastic polymer,Release Sukano S 462 as an antiblocking agent.

FIG. 3 shows a further embodiment of the foil composite material 4according to the invention. This embodiment has the simplest layerconstruction with a single inner layer 3 made of TPC material and twoouter layers 1, 2 made of PETG. One or several of the layers cancontain, as in all other embodiments, usual accessory agents, forexample dyes, UV protection agents or (in the outer layers) antiblockingagents. Antiblocking agents, however, are not absolutely necessary.

Usually it is desired that the inner layer made of TPC material has anas great a proportion as possible in the total thickness of the foilcomposite material, so that the advantageous elasticity properties ofthe TPC material have a good effect. The outer layers 1, 2 made of PETGare usually kept thin because they are to serve for equipping the innerTPC layer(s) with the surface properties of the thermoplastic polymerPETG. Further, the outer layers 1, 2 are to provide the needed stiffnessto the foil, so that this can be further processed in the commonmethods, such as e.g. for printing, handling etc. These properties arefor example the good laminatability, handling without massive danger ofblocking, good printability, etc. From this point of view, the layerthickness of the inner TPC layer should have a proportion of at least40% in the total thickness of the foil composite material. Preferred areproportions of 60 to 80% TPC layer thickness in the foil material layerthickness. In order to be able to achieve these high layer thicknesses,the inner TPC layer is composed of several partial layers usually withthe help of several extruders.

It is in principle possible that both the outer plastic layers 1, 2 andthe inner plastic layer 3 are respectively composed of several partiallayers. Simultaneously, however, it is preferred that the foil compositematerial 4 produced has no more than seven partial layers, since thecoextrusion is more difficult in terms of process engineering, the morepartial layers have to be coextruded with each other. Therefore,preferably either the inner layer 3 or the outer layers 1, 2 consist ofpartial layers, whereby the outer layers respectively should beconstructed from no more than two partial layers, and the inner layershould be constructed from no more than five, preferably no more thanthree, partial layers.

FIGS. 4, 5 and 6 respectively show exemplary layer constructions forcard bodies 5 according to the invention (exploded views). In general,card bodies according to the invention consist of a card core 9 which istypically constructed from one to seven layers. The layers consist ofthermoplastic foils, typically made of PVC, ABS, polyester,polycarbonate, PEC (blend of PC and one or several other polyesters) andthe like. Between the layers and/or in recesses of the layers there canbe located electronic components such as electronic modules andantennas. Other features, such as for example security elements orimprints, can also be provided. The layer construction is respectivelycompleted on the outer side by a cover layer. The foils forming thelayer construction are preferably interconnected by laminating, which iswhy all materials used should be readily laminatable to each other.

FIG. 4 shows an embodiment of a card body 5 according to the inventionhaving a card core 9, consisting of a PET foil 60 (152 μm), onto which,optionally, a coil (not shown) can be imprinted, and two PVC foils 61,62 (240 μm each). The layer construction is completed by the two coverfoils 80, 81 (105 μm each), which consist of the foil composite material4 according to the invention, as was described hereinabove.

FIG. 5 shows another embodiment of a card body 5 according to theinvention. Here, the card core 9 consists of a single PET foil 60 (152μm) having an imprinted antenna (not shown). The PET foil 60 is adjoinedon both sides by the layers 70, 71 (240 μm each). The layers 70, 71 inthis embodiment consist of the foil composite material 4 according tothe invention. The layer construction is completed by the two coverlayers 80, 81 made of a PETG overlay foil (105 μm each).

A further alternative embodiment for a card body 5 according to theinvention is represented in FIG. 6. Here, the card core 9 consists ofthe PETG foils 60, 61 (310 μm each), onto which the cover layers 80, 81(105 μm each) are laminated. The cover layers 80, 81 consist of the foilcomposite material 4 according to the invention.

In FIGS. 4, 5 and 6, the μm-values in brackets respectively denote thethicknesses. It goes without saying that the specified layer thicknessesas well as the specified materials are to be understood only by way ofexample, and that other materials which are laminatable to each other aswell as deviating layer thicknesses and deviating numbers of layers canalso be used. Further, the card constructions are representedsymmetrically in the Figures, which, however, is by no means compulsory.Essential is, that the foil composite material 4 according to theinvention can be both used as a cover layer, as shown in FIG. 4 and FIG.6, and as an intermediate layer, as shown in FIG. 5. Embodiments arealso possible wherein the foil composite material 4 according to theinvention is used only as one of the cover layers and/or as anintermediate layer, and embodiments which have cover layers andintermediate layers which are both made of the foil composite material 4according to the invention. Upon use as a cover layer (overlay foil),the layer thickness of the foil composite material 4 is typically nomore than half as thick as upon a use as an intermediate layer (inlayfoil). As a cover layer the foil composite material according to theinvention is preferably transparent, while as an intermediate layer itis preferably opaque.

Through the employment of the foil composite material according to theinvention as cover layer(s) and/or as intermediate layer(s) in a cardbody, the mechanical properties of card bodies can be decisivelyimproved over card bodies of the prior art. The card bodies can besubjected to stronger and more frequent bending loads without thereoccurring stresses, cracks or breaks of the card body. Stresses arisingfrom the installation of electronic modules, which always cause aweakening of the card body, can also be compensated and thus themechanical properties of the card body improved. The foil compositematerial according to the invention can be employed in the card bodiesinstead of any standard foil. It is itself highly flexible and gives thecard bodies flexibility.

In particular card constructions wherein the foil composite materialaccording to the invention is employed as an intermediate layer, asrepresented by way of example in FIG. 5, have excellent mechanicalproperties, such as excellent strength and stiffness. This becomesevident particularly in the case of actions of impact force, whichotherwise as a rule lead to card breakage. This is presumably caused bythe greater thickness of the foil composite material intermediatelayers, and thus the higher proportion of the foil composite materialaccording to the invention in the card body altogether.

The foil composite material according to the invention is also verystable in itself, i.e. there is a firm bond between the partial layersmade of PETG and thermoplastic copolyester elastomer without any dangerof the partial layers separating from each other upon load. Thisstability can be achieved without producing gradations between thepartial layers by the use of material mixtures. Therefore there is noneed for producing compoundings of granules upon the coextrusion.

The foil composite material according to the invention can bemanufactured inexpensively, and there is a wide spectrum ofthermoplastic copolyester elastomers with different properties availableon the market. The foil composite material made of PETG andthermoplastic copolyester elastomers is easier to process by thecoextrusion method than foils with other thermoplastic elastomers. It isalso characterized by especially simple handling in further processing,i.e. it can for example be printed without any problems and laminated toall common card materials. It also does not tend to block. A specialadvantage that makes the foil composite material according to theinvention excellently suitable in particular for use as a layer in acard body, is the act that the foil composite material can bemanufactured with a very high proportion of thermoplastic elastomer,thereby improving the mechanical properties of the card body in anexcellent manner.

1. A method for manufacturing a foil composite material in the form of acoextrusion of at least one first outer layer plastic material, at leastone second outer layer plastic material, and at least one inner layerplastic material, comprising: merging all the plastic materials in amolten state, and extruding them through an extruder nozzle thatextrudes a foil, to thereby obtain an extruded foil composite material,in which an inner plastic layer is covered on both sides by a first anda second outer plastic layer, wherein the composition of at least onefirst outer layer plastic material is a polyethylene terephthalateglycol copolymer (PETG) or contains a PETG, the at least one secondouter layer plastic material has a composition comprising athermoplastic copolyester elastomer (TPC) or contains a TPC, the atleast one inner layer plastic material has a composition comprising aPETG or contains a PETG.
 2. The method according to claim 1, wherein thecoextrusion is carried out at a nozzle temperature of 210 to 260° C. 3.The method according to claim 1, wherein the extruder flow rates are setsuch that a foil composite material is coextruded, and wherein thethickness of the inner layer constitutes 40 to 80% of the thickness ofthe foil composite material.
 4. A method for manufacturing a card bodyhaving a plurality of plastic layers, comprising: a card core made of atleast one core layer, at least two cover layers for covering bothsurfaces of the card core, and wherein the plastic layers are laminatedto each other in one work operation or in several work operations,wherein there is used as at least one of the cover layers and/or as atleast one intermediate layer the foil composite material.
 5. The methodaccording to claim 4, wherein laminating is effected at a temperature ofbetween 120° C. and 200° C.
 6. The method of claim 4, wherein the foilcomposite material comprises: at least one first outer plastic layer, atleast one inner plastic layer, at least one second outer plastic layer,wherein all the layers jointly form a coextruded composite, the plasticof the at least one first outer layer is a polyethylene terephthalateglycol copolymer (PETG) or contains a PETG, the plastic of the at leastone inner layer is a thermoplastic copolyester elastomer (TPC) orcontains a TPC, the plastic of the at least one second outer layer is aPETG or contains a PETG.
 7. The method of claim 4, wherein the foilcomposite material is made by the method of claim 1.